This invention relates to a chair of the so called reclining type capable of adjusting and fixing freely an angle of inclination of a back rest and a seat plate by means of a gas spring and more particularly, to a chair comprising a stationary frame fixed to a pole brace erected on legs, a back rest frame for mounting a back rest, a base frame for mounting a seat plate, and inclination adjusting mechanism for tilting and fixing the back rest at an optional angle in the condition where a vertical motion of the front portion of the base frame is small and slidably shifting the base frame in backward direction by following the inclination of the back rest frame, and a lever releasing keeping mechanism for keeping the inclination adjusting mechanism in a free condition.
Heretofore, in a chair in which the seat plate is horizontally fixed and only the back rest is reclined, when the back rest is reclined, the gap between the rear end of the seat plate and the lower end of the back rest changed changes. When the back rest is pushed backward while a person is sitting on the seat plate, clothing such as shirts or the like is turned up. If the back rest is on the tilt, the seat plate remains in a horizontal condition so that the body of the person tends to slip over forward which results in an unstable posture of the person and in an uncomfortable seating.
On a other hand, the chair in which the seat plate and the back rest are built in an integral unit and the unit is capable of reclining backward has been proposed, but in a chair having the foregoing construction, the reclining occurs centering around the pole brace as a fulcrum which supports the center of the seat plate, the front end of the seat plate rises according to the tilting of the seat plate, and as the result, the feet float or the seating becomes uncomfortable.
Moreover, in a chair in which the inclination of the back rest or the seat plate is adjusted and fixed by a gas spring, the gas spring becomes free only when the operation lever for switching the push valve of the gas spring is held down by hand which enables the reclining of the back rest or the like to change, and when the gas spring is locked and the back rest is fixed to an optional angular position. Therefore, as described in the foregoing, those conventional chairs have drawbacks which are not suitable for allowing a person to take free postures which relieve tensions by fixing the angle of inclination of the back rest or the seat plate.